The Gene and Linda Voiland School of Chemical Engineering and Bioengineering is hosting a seminar presented by Trent Graham, Ph.D. Student, Voiland School of Chemical Engineering and Bioengineering, Washington State University, Feb. 26, at 4:10 p.m. in ADBF 1002/FLOYD 256 (Tri-Cities).
As an undergraduate, Trent R. Graham studied biological engineering with a focus in molecular bioscience. He participated in a broad range of research at Washington State University (WSU) and worked in a biological systems engineering laboratory, two molecular bioscience laboratories, a chemical engineering laboratory with support from the National Science Foundation research experience for undergraduates (NSF-REU) and at the United States Department of Agriculture, Agricultural Research Service (USDA-ARS). In graduate school, he pivoted to chemical engineering, where he studies ensemble supramolecular speciation in complex liquids with nuclear magnetic resonance spectroscopy (NMR). Trent has received several industry funded, travel grants to present this work at specialized NMR conferences and received awards at international conferences held domestically and abroad. Currently, Trent participates in the Pacific Northwest National Laboratory (PNNL) – WSU Distinguished Graduate Research Program, enabling independent study at PNNL. At PNNL, he is also an active team member in the Energy Frontier Research Center on Interfacial Dynamics of Radioactive Environments and Materials. Trent currently has authored four papers, with an additional six in preparation. In Trent’s free time, he enjoys reading, and in particular, works by Larry Niven and Orson Scott Card.
Quantification of Supramolecular Assembly in Complex Liquids with Pulsed Field Gradient and Magic Angle Spinning NMR Spectroscopy
Many molecules self-assemble through subtle interactions into supramolecular complexes that significantly influence overall liquid structure and transport properties. Such liquids are inhomogeneous at the nanoscale, and are often found in industrial processes including the synthesis of nanoparticles involving the use of phase transfer catalysts, heavy metal extractions in supercritical carbon dioxide, and ion-pairing in concentrated electrolytes. These complexes are in rapid, dynamic equilibrium at timescales prohibiting spectral resolution of discrete species with techniques such as Nuclear Magnetic Resonance Spectroscopy (NMR). Herein, we demonstrate a theory-guided analysis of supramolecular assembly in which diffusion ordered, pulsed field gradient (PFG) and magic angle spinning (MAS) NMR experiments are utilized to quantify the morphology and distribution of supramolecular species in industrially relevant systems. A refinement on the calculation of cluster distributions from ensemble diffusometry is presented and limitations on the use of ensemble measurements to generate cluster distributions are noted. These limitations of ensemble spectroscopic NMR measurements are transcended by novel in-situ NMR experiments wherein the crystallization of an ionic liquid is leveraged to arrest the dynamic exchange of poorly resolved species. The described methodologies and experimental design provide significant improvements in analysis of complex systems and are widely applicable in industrially relevant processes.
